A mass of light grey to white, recrystallized limestone of the Upper Pennsylvanian to Lower Permian Azure Lake Formation (Buttle Lake Group) outcrops over a 280 by 350 metre area on the west slope of Mount Septimus, at the southern end of the Buttle Lake uplift. The limestone is underlain to the southwest by volcanic breccia, tuff and argillite of the Paleozoic Sicker Group and is overlain to the northeast by pillowed basalts of the Upper Triassic Karmutsen Forma- tion (Vancouver Group). Refer to the H-W deposit (092F 330) for a discussion of the revised nomenclature of the Buttle Lake uplift stratigraphy.